This invention pertains to an improved portable heaters used in relatively small enclosures. More particularly, the invention relates to a uniquely configured propane source infrared heater for use in enclosures such as small recreational enclosures, temporary work enclosures, or vehicles. Although the invention was designed for indoor areas, it will be appreciated that it has broader applications and may be advantageously employed in a wide variety of environments without departing from the scope of the invention.
Gas-fired portable heaters are well known in the art and are used in multiple environments. The heater typically includes a housing having a chamber. The housing has an inlet for receiving air into the chamber. Gas is introduced into the chamber to be mixed with the air in order to complete combustion and provide an infrared heating surface. A plenum directs the heat toward a mesh screen and evenly distributes it over the surface thereof. The overall goal in designing such a unit is to achieve a radiant surface that provides even, stable heating over the entire surface.
The use of such heaters is strictly regulated for outdoor only use due to the emission of carbon monoxide. Prior designs in existing portable units are subject to a wide variety of problems. Most importantly, the prior designs are not safe or certified to operate in small recreational enclosures such as tents, truck-caps, fishing huts, trailers, vans, etc. There are a few reasons why the devices found in the prior art are not adequate to perform in such environments. First, the portable heaters that exist today operate at a high pressure generally on the order of 12 psi. Specifically, the pressure from the propane tank through a regulator is necessarily high in order to achieve adequate gas and air flow. In addition to requiring high pressure, previous designs do not have the ability to pass strict combustion requirements at a high and low firing condition and at a reduced pressure. For example, a new standard developed for this product (CSA International 4.98 US) states that xe2x80x9cthe appliance shall not produce carbon monoxide in excess of 0.010 (100 ppm) percent in a room with no air changes occurring during combustion of the amount of gas necessary to reduce the oxygen content of the room to 18 percent by volume.xe2x80x9d In addition, they do not possess an oxygen depletion system (ODS)(Capreci/Part No. 21500). These shortcomings have prevented the portable heaters found in the prior art from adequately performing in small recreational and temporary work enclosures.
Therefore, a need exists to provide a portable infrared heater capable of performing safely in small recreational enclosures and temporary work enclosures.
This invention contemplates a new and improved burner assembly that is capable of performing safely in small recreational facilities such as tents, truck-caps, vans, fishing huts, trailers, etc.
According to the present invention, a portable heater includes an outer housing having a first or front face, a second or rear face, and two sides interconnecting the front and rear faces. An air inlet is located on the front face of the housing, preferably along a lower portion thereof. A gas supply or tank is partially enclosed and supported by the outer housing. A burner venturi, having a cylindrical body extending upwardly at a slight angle, is disposed within the housing. The burner venturi also has a mouth operatively associated with a bottom end of the cylindrical body. Gas is released from the gas supply into the mouth of the burner venturi. At the same time, air is drawn into the mouth of the burner venturi from the air inlet. The air and gas mix thoroughly as they travel upwardly through the burner venturi.
Upon exiting the burner venturi, a baffle directs the air/gas mixture into a plenum to further mix, enter a rear face of a radiant surface, and then ignited on a top surface where combustion occurs. Any conventional means for initially sparking or igniting the air/gas mixture at the burner surface can be used. The burner plenum is heated to an elevated temperature and the radiant surface emits heat to the ambient environment. Combustion products are directed off a deflector shield which reduces the temperature of the products before exiting an outlet at an upper portion of the housing.
The air inlet of the present invention is advantageously designed to provide air flow along the hot burner plenum resulting in an increased velocity of air flow to the burner venturi. As the burner venturi is heated, the thermal properties result in the air/gas mixture passing upwardly through the angled burner venturi creating a chimney type effect. The chimney effect created by the present invention increases the air flow velocity into the burner venturi. In addition, the device reduces pressure from the gas supply and has the ability to satisfy combustion requirements at low fire condition.